Transcript for New Concern and Fears Over Supplement That Claims to Burn Fat

We have a health alert about a popular supplement. The fda is telling people to stop taking it immediately, citing a possible link to liver failure. At least one person has died. The investigation has intensified. And abc's dr. Richard besser is tracking it tonight. Reporter: It's called oxyelite pro. 29 cases of hepatitis, a serious liver disease. Two have needed a liver transplant and one is dead. 80% of those patients took it in the two months before they got sick. Dr. Sarah park is head of hawaii's department of health disease outbreak control, the state where the cases were found. They all took the dietary supplement. Reporter: Hepatitis calls swelling of the liver and is potentially fatal. That's because it makes the liver, a primary filter for toxins in your body, shut down. Nobody yet knows what's causing the problem. The company that makes it, usp labs, says they don't think their product is at fault. That the ingredients have been studied for safety, are consumed in the food supply and widely used in dietary supplements. But supplements don't need to be tested for safety before they are sold to you. So, this is a broad investigation that is going to have to get started. Is it hampered at all by the government shutdown? Reporter: It really is. Some of the state health employees are paid by federal dollars and they're not there. I was told, they're calling cdc and fda experts and they are not answering the phone. The critical question is, why are they seeing this in hawaii and not elsewhere? Is it do to better looking on distribution? They have to answer that question. Rich, thank you. We're going to turn now to a

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